Electromagnetic apparatus.



No. 695,539. Patented Mar.. I8, |902.

` F. B. 000K.

i* ELECTROMAGNETIC APPARATUS.

(Application led Aug. 29, 1899.)

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UNITED STATES FRANK B. COOK, OF

PATENT OFFICE.

CHCAGO, ILLINOIS.

ELECTROMAGNETIC APPARATUS.

SPECIFECATION forming part Of Letters Patent NO. 695,539, dated March18, 1902. Application filed August 29, 1899. Serial No. 728,820. (Nomodel.)

To @ZZ whom it may con/cern:

Be it known that l, FRANK B. COOK, a citizen of the United States ofAmerica, and a resident of Chicago, Cook county, Illinois, have inventeda certain new and useful Improvement in Electromagnetic Apparatus, ofwhich the following is a specification.

My invention relates to certain improvements in an electromagneticapparatus which is especially adapted, although not exclusively, for'use in connection with telephone apparatus, and I shall thereforedescribe and illustrate my invention in connection with such apparatus.

In the central oflice ot a telephone system a switchboard is provided atand by which operators establish connection between the various circuitsof the subscribers as and when called 'upon by any subscriber desiringto be coupled for conversation with some other subscriber. ln order toattract the attention of the operator at the switchboard to the circuitof any given subscriber, annunciators or visual indicators are provided,one for each subscribers circuit, which are operated to display or givea signal by a current generated at the subscribers station extending thecall, which current acting upon an electromagnet of the annunciatoroperates it to display the signal. lt is desirable that the annunciatoror drop be capable of sensitive' and invariable operation by currents ofminimum strength, as the conditions which prevail in telephonie systemstend to impair and reduce the strength ci' the currents in generationand when generated.

The object of my invention is to provide an electromagnetic apparatuswhich shall be ca pable of sensitive action to invariably operate theannunciator by currents of a much less strength than has been possibleheretotore.

My invention has certain other objects in view; audit consists incertain features,which will be fully described, and pointed out in myclaims, reference being now had to the accompanying drawings, in which-Figure l is a side elevation of my improved annunciator. Fig. 2 is acentral longitudinal section. Fig. 3 is an enlarged central longitudinalsection of the central portion of the annunciator, showing thearmature-lever and armature away from the magnet-poles in a position tobe attracted thereby. Fig. 4 is an exterior View of said central portionof the annunciator, also enlarged. Fig. 5 is a crosssection on the linea a of Fig. 2. Fig. 6 is a like view on the line b h of Fig. 2. Fig. 7is an exterior view of a modified form. Fig. 8 is a central longitudinalsection of the same.

My invention broadly consists in an electromagnetic apparatus comprisingsubstantially in construction an inclosing magnetic shell surroundingthe electromagnet and formed in two parts, together with an armatureacted upon by the magnetic poles ot' said shell, whereby the poles ofthe magnetic shell 'are presented in such close proximity to thearmature as to obtain the maximum pull with a minimum current.

My invention also consists in disposing the armature in such relation tothe pole or poles of the electromagnet that said armature is permittedto have a greater range of movement and yet remain always within thefield ot force of the magnet, whereby the armature is invariablyoperated and permitted and given a wider or greater range of movement,and this is accomplished by an operating-current of less strength.

l shall proceed to describe my improvements in connection with theanuunciator of a telephone-exchange.

In annunciators as now usually constructed the one end of one pole ofthe electromagnet acts upon a pivoted armature, which in turn operates apivoted latching-lever engaging a pivoted shutter, whereby the armaturewhen attracted by one end or one pole of the magnet operates the leverto release the shutter, which then drops or falls and in so doingindicates or gives the signal to the operator.

The electromagnet Ais disposed within the tubular magnetic shell B,whichlatter is made in two parts B2 and B3, each secured to the end of thecore A2 of the electromagnet by the screws A3 and Ai. The armature D isring-shaped, surrounds the electromagnet A and its shell B, and ispivoted approximately at the center D2 to diamagnetic pivot-pieces d d;the pivot -screws c c, Fig. 5, passing through diamagnetic pieces ff onthe arman IOC) Vzo

ture and entering said pivot-pieces. By this means the armature ismagnetically insulated from the magnetic shell B and virtually made upof two parts or pieces isolated from each other. The pivot-pieces d dare held by the diamagnetic shield g. Angular-shaped polepieces J and J2are secured on or formed, respectively, with the parts B2 and B3 of theshell B on the upper and lower sides thereof, and the poles of themagnet are therefore located, respectively, above and below the pivot D2of the armature D and presented to opposite sides and vertical ends ofsaid armature. The end portion of each of the parts B2 and -Bs of themagnetic shell in proximity to the armature D are cut away, as shownmore clearly by the dotted lines of Fig. 3, to form the pole-pieces Kand K2, which are thus beneath or within the ring-armature D. By reasonof the weight of the latch-lever E the armature D tends to remain in avertical position away from the pole pieces J J2, as shown in Fig. 3. Itwill be observed, however, that when in this position the armature is atthe same distance from the pole-pieces K and K2, and therefore thesepoles exert aY pull immediately upon the armature D, theV poles J and J2also supplementing and increasing this pull. YThe armature alwaysmaintains thesame slight'relative distance from the pole-pieces K and K2in all its kassumed positions and notwithstanding the armature is givena wide range of movement it is always immersed within the magnetic fieldof the pole-pieces K K2. The armature as ordinarily used at present ispivoted at its upper or lower end in proximity to the magnet, andtherefore a part of the energy of the magnet is wasted in exerting apull upon the stationary pivot-point of the armature. Also the outer endportion of the armature in such a construction is relatively distant orremotel from the pole of the magnet and cannot be given a wide range ofmovement, as it would then be brought without the field of force of themagnet.

In my construction as shown in connection with the annunciator thearmature is preferably centrally pivoted and a pole presented above andbelow said pivot and on either side of the armature, certain 'of thepole-pieces being arranged in suchrelation to the armature that italways remains at the same distance from said pole-pieces, and thereforealways immersed in the eld of fo'rce thereof to be immediately actedupon thereby, the other pole-pieces supplementing'and exerting anadditional pulling force. The pole-pieces unitedly exert an inuencewhich causes the armature to rotate on its pivot into the position shownin Figs. l and 3, thereby lifting thelever E to release the shutter H.

It will also be observed that I Aobtain a greater leverage in actingupon the armature, because the pole-pieces below the pivot exert a pullupon the lower lever-arm of the larmature in one direction, and the polepieces above said pivot exert a pull upon the upper lever-arm of saidarmature in an opposite direction, the combined iniluence of the twosets of pole-pieces resulting in the rotation of the armature on itspivot and the lifting of the latching-lever.

In Figs. 7 and 8 I have shown a form in'` which the pole-pieces J and J2are not employed, in whichk case it is not necessary to divide thearmature into two parts by the diamagnetic pieces f f, as is done withthe form previously described. It will be particularly observed that byreason of this construction the armature is always in close proximity tothe electromagnet-poles, and thereby a maximum pull is brought to bearupon the armature by the poles with a minimum current. Again, as theelectromagnet is surrounded by a heavy metallic shell, should the coilburn out under excess of current the shell would protect the otherportions of the apparatus from injury by fire.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is-

1. In an electromagnetic apparatus, a twopart armature approximatelycentrally piv.

oted, an electromagnet and a plurality of polepieces of said magnetarranged on eitherside of said armature and above and below the pivotthereof, a latching-lever anda drop or` shutter normally held by saidlever.

2. In an electromagnetic apparatus, a twoon an axis located between thepoles of said two-part shell.

4. In an electromagnetic apparatus, a twopart magnetic shell, anelectromagnet connected therewith, and an armature centrally pivoted andpositioned between the' poles vof the shell.

5. In an electric magnetic apparatus, a twopart magnetic shell, anelectromagnet connected therewith and a centrally-pivoted'ringy shapedarmature positioned between the poles of the shell and surrounding theelectromagnet.

'6. In an electromagnetic apparatus, a twopart magnetic shell, anelectromagnet connected therewith and a centrally-pivoted ringshapedarmature which surrounds the electromagnet and the pole-pieces of theshell whereby said armature remains within the field of force of saidpole-pieces.

7. In an electromagnetic apparatus, anlag- IOO IIO

netic shell formed in two parts each of which is connected with theelectromaguet and each having a. pole-piece and a two-pmt armaturetogether Withsupplemental pole-pieces on the ends of the magnetic shell.

S. In an electromagnetic apparatus, a tWopart magnetic shell, anelectromagnet connected therewith and L ring-shaped armature, suitablypivoted encircling said electromagnet and positioned between the polesof the 1o shell.

Signed by lne at Chicago, Cook county, Illinois, this 26th day ofAugust, 1899.

FRANK B.. COOK.

lVitnesses:

CHAs. C. BULKLEY, L. W. BULKLEY.

